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Deghosting of towed streamer and OBC data

This paper discusses the theory, strategy, and numerical tests for deghosting towed streamer and ocean bottom cable (OBC) data. It also explores new techniques for both types of data. The paper includes details on M-OSRP projects such as wavelet estimation, deghosting, interpolation and extrapolation, and more.

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Deghosting of towed streamer and OBC data

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  1. Deghosting of towed streamer and OBC data Jingfeng Zhang, Arthur B. Weglein M-OSRP Annual Meeting, University of Houston March 31 – April 1, 2004

  2. Outline • Motivation • Theory overview • Towed streamer deghosting • Theory and strategy • Numerical tests • Ocean bottom deghosting • Conclusions and plans • Acknowledgements

  3. Motivation • Towed streamer deghosting • Conventional methods • New techniques • Ocean Bottom deghosting • Conventional methods • New techniques

  4. M-OSRP projects • Wavelet estimation • Deghosting • Interpolation and extrapolation • 3-D multiple attenuation • Inverse scattering sub series for imaging • Inverse scattering sub series for inversion

  5. Theory Overview Weglein et al. (2002) F.S. M.S. earth

  6. Note (1)

  7. Note (2) Green’s Second Identity

  8. Note (3) F.S. Deghosting formula Eq. (1) M.S. Weglein et al. (2002) earth

  9. Note (4) F.S. Field prediction Eq. (2) H. Tan (1992) and A.Osen et al. (1998) M.S. Scattered field prediction Eq. (3) earth H.Tan (1999), Weglein et al. (2000)

  10. Note (5) F.S. Wavelet estimation Eq. (4) Weglein and Secrest, (1990) M.S. earth

  11. Notes conclusion

  12. Towed streamer deghosting(Theory) Weglein et al. (2002) F.S. Pseudo-M.S. M.S.

  13. Towed streamer deghosting(Theory) H. Tan (1992) and A.Osen et al. (1998) H. Tan (1999), Weglein et al. (2002)

  14. Towed streamer deghosting(Theory) K=0.3 (f~72Hz) Pseudo-M.S.

  15. Towed streamer deghosting(Theory)

  16. Towed streamer deghosting(Theory) (2) (3)

  17. Towed streamer deghosting(Theory) Exact A(w)=1.0 Offset x (m)

  18. Towed streamer deghosting(Numerical tests) F.S. (0,2) 6.0m M.S. 300m c1=1500m/s c2=2250m/s

  19. Ricker wavelet

  20. Total data received At (1500,6.0) At (0,6.0)

  21. Wavelet approximation

  22. Wavelet approximation

  23. Depth sensitivity K=0.3 (f~72Hz) A1(w)=(2,3),A2=0.04*A1,A3=0.03*A1,A4=0.3*A1 Pseudo-M.S.

  24. Red solid: Exact Up-going P (5.8m) Blue dash: Predicted Up-going P (6.3m) (using wrong depth 6.5m)

  25. Red solid: Exact Up-going P (5.8m) Blue dash: Predicted Up-going P (6.3m) (using wrong depth 6.5m)

  26. Red solid: Exact Up-going P (5.8m) Blue dash: Predicted Up-going P (6.3m) (using wrong depth 6.5m)

  27. Red solid: Exact Up-going P (5.8m) Blue dash: Predicted Up-going P (6.3m) (using wrong depth 6.5m)

  28. Ocean bottom data deghosting(Theory) Weglein et al. (2002) • Both and (particle velocity) are measured. • Noise on geophone • Coupling issue and scale factor : actually measured are and

  29. Ocean bottom data deghosting(Theory) Troublesome and historic impediment measurement Two stable measurements Triangle relationship Wavelet estimationWeglein and Secrest, (1990)

  30. In this procedure: Using and A(w) to calculate Deghosting Ocean bottom data deghosting(Theory)

  31. Conclusions for towed streamer deghosting • If source wavelet is available, the deghosting algorithm performs well, as expected. • With an approximate wavelet, the algorithm still works well. If the rough duration of the source wavelet is known, very good deghosting result can be obtained. • Field data test is planned for 2004.

  32. Plans and Acknowledgements • Numerical tests on the proposed procedure for ocean bottom deghosting using both synthetic and ocean bottom cable field data. • We thank M-OSRP sponsors for supporting this project. • Special thanks to Nizar Chemingui and Jon Sheiman for their interests. We thank A. de-Hoop for providing references and Hing Tan for valuable discussions.

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